The great Norwegian historian Odd Arne Westad’s The Cold War: A world history is – for my money – the best general introduction for the interested reader. It’s genuinely global in scope and touches on many places and themes that previous general works (like John Lewis Gaddis’s The Cold War) ignored or elided. Lorenz Luthi’s Cold Wars: Europe, Asia, Middle East is also great, but slightly more academic in style and form, and much more granular and detailed.
On more narrow topics, I always find it hard to look past stuff like the brilliant Kate Brown’s Plutopia: Nuclear Families, Atomic Cities, and the Great Soviet and American Plutonium Disasters. It’s a wonderful combination of diplomatic, political, social, and cultural history that draws out some remarkable conclusions about the nature and impact of the nuclear age in the United States and the Soviet Union.